Semiconductor transistors, in particular field-effect controlled switching devices such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) or an Insulated Gate Bipolar Transistor (IGBT) have been used for various applications including but not limited to use as switches in power supplies and power converters, electric cars, air-conditioners, and even stereo systems. Particularly with regard to power devices capable of switching large currents and/or operating at higher voltages, low switching losses are often desired. In order to reduce switching losses, there are ongoing developments to reduce distances between neighboring unit cells of power devices. For example, the lateral distance between a trench gate electrode and the contact to source region and body region of the transistor may be reduced using self-aligned techniques. However, this typically requires that the oxide isolation to the source metallization has to be arranged in the trench resulting in a higher process variation. To compensate these variations the vertical depth of the trench may be increased. This results however in higher capacitances. Accordingly, switching losses may be increased.
Accordingly, there is a need to provide improved methods for forming self-aligned contacts of semiconductor components.